Die for molding mica rings



L'WE SGB Feb. 24, 1931. L. T. FREDERICK DIE FOR MOLDING MICA RINGS Fi led June 15, 1928 LOUIS T. FREDERICK, OF vALPAnarso, INDIANA} ASSIGNOR, BY MESNE essremannrs, TOGONTINENTAL DIAMOND 'GOMPANY, or ivnwelair, nELaWARnA COR-' Patented Feb. 24, 19 31 um'rs s'rrss PORATION OF DELARVAEE masses matron arc-Imme- IvIIfJA n nes 2 Application filed June s, 1928.] Serial ira'e'saesa. r

I My invention relates in general to apparatus for producing articles from sheets of semiplastlc material and has more particular reference to a machine for forming articles such 7 as insulating rings for the commutators of dynamo-electric machines. Specifically, my

invention resides in providing certa1n'im-" provements m the apparatus forming the subject matter of'my co-pending application Serial No. 147,710, filed November 11, 1926, whereby the operation of the saidapparatus is improved so that formed objects may be produced more easily and surely, and my present application forms a continuation, in

part, of my co-pending application aforesaid. In my aforesaidco-pending application I have shown a device for pressing out insulat I ing rings from a stock of mica'discs and one of the objects of my present invention is to provide a novel clamp member whereby the mica discs may be securely held in position in the forming die during the formingoperation so that the displacementof themica;

discs during the forming operation-and the consequent formation of'defective objects may be substantially prevented.

Another important object of my invention ing member.

' grooves in the walls ofthe die in position so i as to form beads in the sides of the formed article whereby thesame may be retained in tien with theaccompanying Still another object ofmy invention is to provide, in a forming'die, a resiliently receding clamping member adapted to co-operate,

with a fixed portion of the forming die to securely clamp material in position inthe die during the forming operation in order to prevent the displacement of the material.

v Still another object of, my invention i is to provide,-in a die for pressing plastic material,

the die after'the retraction ofthe forming -member. 7 v i Y Numerous other objects and advantages of the invention will be apparent from the fol-' lowing description which, taken in conneccloses a preferred embodiment,

rawings, dis- Referring to the drawings:

Figure 1 is a vertical section taken through i a tormin'g die embodying my invention, the

being shown in relatively openflposrsition; and p p l v F1gure-3 is an enlarged vlew OfPOIlilOIlS of the device as shown-in Figure 2';

To illustrate my invention I have shown on the drawings a forming die comprising arel atively movableffo'rming member and'a-re1a "tively stationary member. The r'el'ativelystationary member comprises a recessed die 11 suitably mounted to a frame or'base 13and havin a core 15 and a 'recedinm die ortion 17 arrangedwithin the recess. The movable r member comprisesa pro ectmg d e member 19 suitably secured toa vertically reciprocable ram 21 in positionto'co-operate with the relatively stationarymembe'r'to form a closing mold upon'the downward projecting movement of the ram 21. The recessed die 11 has walls divergingupwardly, thus forming a substantially conical recess or chamber in which the work material-may be molded.

The core 15 is secured to the bed plate or frame 13 centrally within the conical recess and is or may be suitably anchored to the bed" plate asby the bolt illustrated in the draw ings; A receding d e POIUOILT'Z also 1s arranged within the conicalrecess." This die is annular in form and embraces the'core, being 1 adapted to slide vertically thereon; V l/Vh'en this'recessed die is depressed to its lowermost position, as shown in Figure 2, it'rests upon the bed plate 13 and in conjunction with the conical recess of the dieforms a substantially V-shaped annular groove. The receding the portion 17 is control-led by pins27 which'pass through the bed plate 13 and contact at their upper ends with the underside ofthereceding die. The lower ends of the pins'27 eng'agej an adjuster block 29 which lies in suitable groove or channel formed'in the 'bed. plate vertically beneath the die 11 The "adjuster block is secured as by a pin Sl t-oi the lower end of a rod 33 which extends upwardly through a journal formedin the bed plate a l h Ila tically recipro'cable member 21 by means of a coupling 41 and is annular in cross section,

1 having an axial channel 43 arranged therein,

and the lower annular edge of the member 19 is substantially V-shaped in cross section.

I arrange a plunger 45 centrally within the pro ecting die 19. This plunger isadapted for vertical movementrelative to the die 19 which is suitably formed to provide a ournal 47 for this purpose. The plunger is carried by a shaft49 extending upwardly within the channel 43 and is normally urged downward- 1y with respect to the die member 19 by means of a spring 51 housed within thechan nel 43 and; engaging: at opposite ends a shoulder 53 formed in l the plunger and a .shoulder 55 formedattheyupper end of the V channel 48. The shoulder 55 defines a circular opening through which the upper end of the shaft lQeXtends and aunt 57 is threaded upon the upper end of the shaft as to limit the downward-movement of the plunger 45' 7 under the urge of the spring.

The core 15of therelativelystationary die member is-p'rovided with an upwardly projecting central pin 23 which is adapted to engage through apertures formedcentrally in the work material 25 in order to center the same above the conicalrecess of the die member 11 and in positionto be molded therein.

It will be apparent that when the rain 21 moves downwardly, the rod 33 and the adjuster block 29 will be. allowed to descend under the influence of gravity. The receding portion 15 of the relatively stationary die centrally in the plunger and the peripheral portion-61 of the lower. end ofthe plunger co-acting-with. the core'member 15 110 se--" curely clamp the sheets. of moldable, material firmly'in place. Further downward movement of the ram 21 resultsinthe proon the plunger and depressingthe outer; portions of thediscsz of moldable. material into.

* the V-shaped groove formedby "the cooperati-ngf portions. ofthe: die: portion ll. and

I invention.

17, the inner edge of the die member 19 cooperating With the edge of the core 15 to shear off the outer portions of the moldable material immediately before the outer portions are pressed into the groove. Itwill be apparent that this construction allows the discs of moldable material to be securely clamped by the co-operation of the plunger and the core before the outer portions65 are sheared off from the-central portions 63. This insures that the preformed discs of moldable material are properly positioned in the mold during the forming operation to the end that the formation of-imperfect objects may be eliminated, and the recessed die has one or more shallow annular grooves 66,

theplastic material is-compacted. into the recessed die 11 by-the forming die v19 the grooves. 66' will cause small beads to be formed injthe sides of the molded object. These. beads. engagein the grooves and are suflicie'ntly'strong to retainthe molded object-in the'recessed diewhenthe forming die 19 is-withdrawirand until the receding,

die portion 17joperates to eject the object from the recessedrdie -11; 1 3

I- have dis'coveredthat thepercentage of rejected objects, when the forming die of my inventionis used to form insulating rings which of necessity must-be accurately made, may beappreciably reduced, The cost of making-mica productsis consequently greatly reduced.-v

7 It isthoug-ht that. the invention and numerous of itsimportant advantages will be apparent from the foregoing description and it will; be. apparent also thatv numerous changes-maybe made in-the formation, con- Structionand arrangement ofthe parts with out departing from the spirit and scope of the invention or sacrificing any of. its material advantages, therform herein described being merely a preferred embodiment of the I do not herein claim the novel construction and arrangement of thevarious parts of the forming die itself, since the same forms thesubject matter of my co pending' application, Serial'No; 117,710, filed Novemberll, 1926,;

. Hi l ib m invention what i i asfnew'and' desire to secure byjLet- 1. In a forming die comprising a die mem- 1 her and a relatively movable-cooperating die member, means formed in one .of said membersforcentering astack of variesizedsh eets thereon, cooperating means. mounted in the other of said relatively movable.- die members 3.;

and adapted to clamp the sheets in centered position in saidfirst mentioned diememher as a part of the molding operation.v

2. In a forming die comprising a pair of s relatively movable die members adapted to cooperate the mold material tlierebetween. means formed in one of said die members for centering a stack of vari-sized sheets thereon, the other die member having means adapted to cooperate with the centering means to seof said die members.

I 3. In a forming die comprising a relatively member and adapted to co-operate with the centering means of said die member prior to and throughout the molding co-operation of said movable members.

4. In a device for molding plastic sheets, a recessed die provided with a groove, a co operating relatively movable member for forcing a stack of work sheets into the groove, co-operating means formed and arranged in the die and the relatively movable member, and including a clamping member carried by one of said members whereby to secure the work sheets in centered position between said co-operating die and relatively movable member, during the molding 'co-operation thereof.

5. In a device for molding plastic sheets, a die member having an annular groove, a relatively movable projecting die adapted to co-operate with said die member to force work sheets into said groove, co-opera-ting means formed and arranged in the die memher and projecting die, and including a projection formed in one of said'die members and means yieldingly carried in said other 'die member to co-operate with said projection whereby work sheets may be centered and clamped securely between the dies, during the molding co-op'eratioii thereof. j 6. In a machine I for making insulator rings, a recessed die member having an annular groove and itC-ilil' ial portion within said groove, said centralportiouhaving a projection formed therein to engage and cen-' ter perforated sheets-in the recessed die,aii annularprojecting die adapted to co-operate with said recessed die member to form work sheets in said groove and a clamping member resiliently carried by said projecting die in cure the moldable sheets in centered position thereon as a part of the moldinggoperation' rings from plasticworl; sheets, adie compris ng a stationary central portion, a depr'essible annular portion encircling said central portion and a, substantially. conical peripher'a'l portion adapted to co-operate with said depressible annular portion to provide an annulargroove, and an annular project- -ing die adapted to co-operate with said first mentioned die, sai'd' projecting' die having an annularportionadapted to force work sheets =into said groove, and a yieldi i depressible member adapted to clamp the work sheets to be molded against said central portion during the forming 'co-operation of said pro ecting die and said stationary die member; V

8. In a machine of the class Cl3SC1lb6d,;t recessed die, a receding diewhicli, when'depressed, forms an annular groove in conjuiiction.with the recessed die and an aiinuiar' pro ecting die-for forcing moldahleinatei'iai into said groove to form a molded object, said recessed die being provided with a groove arranged therein opposite the sides of the molded object in position to receive projections formed in the sides of the moldedobject whereby the nioldedobject may be retained *1 in the groove upon the retraction of the'proejecting die.

9. In a machine recessed die providedwith an annular depression, a projecting die for forcing 'moldable material into said depression to form a moldedobject, said recessed die being 'providjed' 01?" the class, described, a I

with a groove arranged therein in the sides.

of the depression in'positioiito receive proections formed n the sides of the molded object whereby the molded object maybe re tained in the grooveupon the retraction of the pro ecting die. a I 10. In a IHaGlHHGIOI molding astaclr superposed plastic sheetsofvarious size, to

operating mold.v portions adapted to "engage opposite vends of the staclrtomold-the sheets relatively movable means formed: and-ar- 'angedin' the other portions andadapt'ed to co-operate with said centering means to secure the sheets in centered position.

11. In a machine for molding a stack of superposed plastic sheets of various size,co-'

operating mold portions adapted to engage opposite ended the stackto mold the sheets therebetween, a centering means arrangedin one of said co-operating portions for center- I 7 ing the sheets in said portion and fdepressible means formed and arranged in the other portionand adapted to cooperate with said centering means to secure the sheets in centered position.

1-2.'In a machine for molding a stack of i superposed plastic sheets of various size, co-

operating mold portions adapted to engage opposite ends of the stack to mold the sheets 4 V i r 1,793,603

therebetween, a centering pin arranged in 'one ofsaid co-operatingportions for centering the sheets in saidportion and depressible means formed and arran'gedin the other portion and adapted'to co-operate with said centering pin to clamp the sheets in centered 1 position. p 7 r v 13. In a machine for making insulating rings'from plastic Work sheets, a die comprisio ing a central portion, a relatively depressible annular portion encircling said central por' tion and a substantially, conical peripheral portion adapted to co-operate with said depressible portion to form an annular groove, and a relatively movable'die adapted to cooperate with said first mentioned die, said relatively movable die having an annular portion adapted to forcework sheets into said groove and a yielding depressible portion :0 adapted to clamp worksheets against said central portion during the ringi'ormingcooperation of said dies,';saidjannularportion of the relatively movable die being adapted to co-operate with the central portion o fsaid first mentioned die to punch out the centers of the plastic sheets during the molding operation. a

14. 'In a machine for making rings from v plastic worksheets, a die comprising a cen- 30 tral portion, a depressible annular portion encircling said'eentral portion and a peripheral portion adapted to co-operate with said depressible portion to provide anannular groove, said central portion being provided with means formed therein and adapted to engage the work sheets to center the same in the die, anda relatively movable die member adapted to co-operate with said first mentioned die, said die member having anan- 40 nular portion adapted to force work sheets into said annular groove of the first mentioned die and a yielding depressible portion arranged'to clamp the Work sheets incenteredposition in the firstmentioned die, as; 4.3 a partof the ringforming operation.

1 In witness whereof, I have hereunto subscribed myn'ame. I I

LOUIS T. 'FREDERIGKJ 

